The invention relates to an apparatus for monitoring and securing danger zones on power-driven textile machines, in particular spinning preparatory machines, for example, bale openers for textile fibre bales.
Power-driven textile machines typically have movable machine parts in which a security device comprises optical monitoring means which monitor a movable danger zone to form a movable protection zone such that a person and/or an objected intruding into the danger zone triggers a switching operation.
In practice, devices for protecting dangerous work elements are present on textile machines, for example, on what are called bale strippers. In the textile industry, especially in spinning preparation, machines for working-off fibre bales standing on the ground are known. Since the work elements used there, for example, stripping rollers, are by the nature of the system located at constantly changing positions and cannot be covered, they represent a considerable danger, inter alia for the personnel operating the machines. The working areas of the machines are therefore nowadays amply guarded by suitable installations, for example, a plurality of light barriers. Owing to the technology used, the complete working area is always inaccessible and can only be entered when the machine is at a standstill and production has been interrupted. Since the laid-down bales are often contaminated with foreign bodies, it would be desirable to be able to remove these without having to interrupt operation of the machine. The drawback is that an interruption leads in some cases to considerable production losses.
In the case of a known apparatus (EP 0 379 465 A), the problematic danger area is shielded by sensors and/or mechanical means. For that purpose, protection means in the form of sensors are provided, which cover a monitoring area laterally below and/or frontally below or directly below the movable working-off element. A plurality of sensors, for example, infrared sensors, which are disposed more or less all the way around the stripper element, create a kind of protective curtain. This is intended to be controlled in such a way that the fibre bales are not detected, but a person entering the area is. All sensors are located on moving parts, in particular the tower and the stripper element, of the machine, i.e. there is a mechanical connection (linking) between the sensors and the machine. One disadvantage is that the sensors have to be moved to produce movable protection zones. In particular it is problematic that the sensors and evaluation systems are secured to the moving machines or machine parts subjected to quite considerable vibrations, which leads to disruptions and dangerous failures of the safety system.